Tile Calculator: 8 × 12 ft room
Work out how many tiles and boxes you need for a floor or wall, with a waste allowance and a rough cost.
// Bill of materials
Costs are rough, materials only — edit the price to match your quote.
Pre-filled for a 8 × 12 ft room. Change any value to recalculate, or start from scratch.
How it's calculated
Area = width × length. We add your waste allowance, then divide by the coverage of one box and round up — you can only buy whole boxes. Tiles needed is the area (with waste) divided by the area of one tile, rounded up.
Worked example — 8 × 12 ft room
- Room width
- 8 ft
- Room length
- 12 ft
- Tile size
- 12 x 12 in (1.0 sq ft)
- Waste allowance
- 10 %
- Tile price
- 3.5 $/sq ft
Nearby sizes
| Room size | Boxes to buy | |
|---|---|---|
| 8 × 8 ft room | 5 boxes | Open |
| 8 × 10 ft room | 6 boxes | Open |
| 8 × 12 ft room (this page) | 8 boxes | |
| 10 × 10 ft room | 8 boxes | Open |
| 10 × 12 ft room | 9 boxes | Open |
| 10 × 14 ft room | 11 boxes | Open |
| 10 × 16 ft room | 12 boxes | Open |
| 12 × 12 ft room | 11 boxes | Open |
| 12 × 14 ft room | 13 boxes | Open |
| 12 × 16 ft room | 15 boxes | Open |
| 12 × 18 ft room | 16 boxes | Open |
| 12 × 20 ft room | 18 boxes | Open |
Tips for buying tile
- Buy at least one extra box beyond the calculated number and keep it — dye lots change, and matching a cracked tile years later is nearly impossible.
- Use 10% waste for a standard straight lay, 15% for a diagonal layout, and up to 20% for herringbone or lots of corners.
- Measure the room, don't trust the listing square footage — closets, alcoves and out-of-square walls all change the count.
- For large-format tile (18 in and up), order 15% waste; big tiles crack more on cuts and can't be salvaged.
- Check the box for the actual coverage and the dye-lot number before you leave the store; coverage varies by tile.
- Order thin-set and grout to match your total square footage, not the box count.
Frequently asked questions
How many tiles are in a box?
It depends on the tile size — a box is sold by square-foot coverage, not tile count. A 12x12 box is usually about 15 sq ft; an 18x18 box about 13.5 sq ft. This calculator uses realistic box coverage for each size.
How much extra tile should I buy for waste?
10% is standard for a straight lay. Go to 15% for diagonal layouts, large-format tile, or rooms with many cuts and corners, and up to 20% for herringbone.
Does this work for walls too?
Yes — enter the wall's width and height instead of the floor's width and length. The math is the same: area with waste, divided by box coverage.
Why round up to whole boxes?
Stores sell full boxes only, and partial boxes from another dye lot may not match. Always round up, and keep the leftovers for future repairs.